The MRI apparatus is an imaging diagnostic apparatus which magnetically excites nuclear spins of an object set in a static magnetic field with RF (radio frequency) signals having the Larmor frequency and reconstructs images based on NMR (nuclear magnetic resonance) signals generated due to the excitation.
In the MRI apparatus, a direct sampling method for detection processing of MR signals is proposed. The direct sampling method is a signal processing method, which applies A/D (analog to digital) conversion directly to analog signals without any frequency conversion, for a detection. When MR signals are directly sampled, digital signals are detected using detection carriers of MR signals, produced by a DDS (direct digital synthesizer). The DDS is a circuit which digitally generates an arbitrary waveform and/or a frequency.
It is important to reduce noises and errors, which are superimposed on MR signals, in order to generate MR images with high quality.
Accordingly, an object of the present invention is to provide a magnetic resonance imaging apparatus and a magnetic resonance imaging method which can obtain MR signals, in which noises, errors or the like have been further reduced, when the MR signals are received by the direct sampling method.